CVE-2015-9070 in Android
Summary
by MITRE
In all Qualcomm products with Android releases from CAF using the Linux kernel, a buffer over-read vulnerability exists in a TrustZone syscall.
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Analysis
by VulDB Data Team • 11/08/2019
The vulnerability identified as CVE-2015-9070 represents a critical buffer over-read condition within the TrustZone secure execution environment of Qualcomm Android devices. This issue affects all Qualcomm products that utilize Android releases from the Code Aurora Forum (CAF) and incorporate the Linux kernel framework. The vulnerability specifically resides within the TrustZone syscall implementation, which serves as a crucial interface between the secure and non-secure worlds of the device's processing environment. TrustZone technology is designed to provide a secure execution environment for sensitive operations while the main processor operates in a less secure state, making this vulnerability particularly concerning for device security.
The technical flaw manifests as a buffer over-read condition in the TrustZone syscall handler, where the system fails to properly validate input data lengths before processing. This allows malicious actors to potentially read data beyond the allocated buffer boundaries, potentially exposing sensitive information or enabling further exploitation. The vulnerability stems from inadequate bounds checking within the kernel-level syscall implementation, where the system does not properly enforce buffer size limitations during TrustZone communication. This type of vulnerability falls under CWE-129, which specifically addresses insufficient validation of length of inputs, and represents a classic example of improper input validation leading to memory safety issues. The flaw exists at the intersection of secure and non-secure processing domains, making it particularly challenging to detect and mitigate.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can potentially enable attackers to gain unauthorized access to secure processing elements within the device. When exploited, the buffer over-read could allow adversaries to extract confidential data from the secure world, potentially including cryptographic keys, user credentials, or other sensitive information stored in TrustZone memory. This vulnerability particularly affects devices where the Linux kernel interfaces with Qualcomm's secure processing elements, creating a potential attack vector for privilege escalation or information extraction. The impact is amplified because TrustZone is designed to protect against such threats, making this vulnerability particularly dangerous as it undermines the fundamental security assumptions of the secure execution environment. According to ATT&CK framework, this vulnerability could be leveraged for privilege escalation and credential access through the T1068 technique involving local privilege escalation and T1552 for credentials in files.
Mitigation strategies for CVE-2015-9070 require a multi-layered approach focusing on both immediate patching and architectural improvements. Qualcomm and device manufacturers must implement kernel-level patches that correct the buffer over-read condition by enforcing proper input validation and bounds checking within TrustZone syscall handlers. System administrators should ensure that all affected devices receive timely security updates, as the vulnerability exists in the core kernel components that cannot be easily bypassed through user-level configurations. The fix should include implementing proper buffer size validation, adding memory protection mechanisms, and potentially introducing additional checks to prevent unauthorized access to secure processing elements. Organizations should also consider monitoring for unusual syscall patterns that might indicate exploitation attempts, while implementing network-based detection measures to identify potential attacks targeting this specific vulnerability. The remediation process must be carefully coordinated across the entire supply chain, from chipset manufacturers to device OEMs, to ensure comprehensive protection against this TrustZone-based buffer over-read vulnerability.